Mini-Winch for FES

As a snow skier, I think that is quite cool. All that site needs is a rope tow back to the top of the hill... �

At 15:47 05 March 2020, Mike N. wrote:
Well with the right hill and some head wind...
https://youtu.be/zdCGb9-vjck

Slightly more on Paul's original topic, at the site where the bungee clip
was shot (Long Mynd in UK) on slightly less windy days, they winch launch
to around 300' straight onto the hill.

No 'Mini-Winch' though - they use a standard, full power Skylaunch winch,
which the also use on their longer runs when the wind is not on the hill.

https://www.youtube.com/watch?v=tGeUFJUQlaQ

On Thursday, March 5, 2020 at 1:22:48 AM UTC-5, son_of_flubber wrote:
I'd rather take my chances on something that would accelerate the glider 0-50 knots in 50 meters with the FES running from the very start of the roll. This would increase available runway ahead for launch failure and conserve a bit of battery power. Fully automated with pilot pushing the go button.


This is really the idea right here. As we increasingly embrace self-launch eGliders, I think we'll see more and more gliders operating out of small airports without the benefit of a club. Thus, what's missing in the conversation is a consideration of the CONOPS (CONcept of OPerationS) for single-person launching.

Gliders have a major limitation in requiring a team to get a single pilot airborne. Having a catapult, which terminates before the runway begins, would get the plane airborne without requiring outside help. It could be semi-permanently installed and not require setup or teardown. The energy needed to accelerate a 300kg plane to 25m/s fits in a battery the size of a tangerine.

When the planes are reported as typically using only 20% of their packs to go fly, I feel this tells us that the major risk isn't climb out, it's takeoff.

Ignoring the risk imparted by the catapult, there are several consequent risk reductions:

1) At a 10% climb grade, a catapult on a 3000' runway would allow a plane to reach 100' with 2000' of runway to spare. An engine failure suddenly becomes a very easy straight-ahead recovery. Contrast this to a more leisurely ground roll on grass which eats up 1000' and where an engine failure at 100' is a real cause for sphincter puckering.
2) For FES-style systems, the prop can be started once off the ground, eliminating the possibility of a ground strike
3) No chance of ripping the wings off the plane due to an over-exuberant winch operation
4) Reduced chance of ground-looping on roll-out, esp. in cross-wind scenarios.
5) Everything that goes wrong goes wrong at low altitude at low speeds
6) Does not impact the runway or leave anything on or near the runway

Relatedly, any kind of automated winch or autotow system requires serious thought about what to do with the launch system once the pilot flies away. A catapult doesn't have this problem since it is installed before the threshold.

I'm not saying getting the catapult right would be easy, but it definitely has a different operational spec than a winch or autotow.

I'm not saying getting the catapult right would be easy, but it definitely has a different operational spec than a winch or autotow.

Heck, let's go for altitude also! Try the Trebuchet. Judging by the altitude Monty Python got using a cow, you ought to be able to fling a 1-26 at least Silver Distance!

On Thursday, June 4, 2020 at 6:55:24 PM UTC-4, wrote:
I'm not saying getting the catapult right would be easy, but it definitely has a different operational spec than a winch or autotow.

Heck, let's go for altitude also! Try the Trebuchet. Judging by the altitude Monty Python got using a cow, you ought to be able to fling a 1-26 at least Silver Distance!

Register that glider in the Isle of Man so it can have the registration M-OOOO.

On Thursday, June 4, 2020 at 6:38:23 PM UTC-4, Kenz Dale wrote:

3) No chance of ripping the wings off the plane due to an over-exuberant winch operation

That possibility is reliably eliminated by a calibrated weak link in the winch launch rope.

On Thu, 04 Jun 2020 21:07:02 -0700, son_of_flubber wrote:

On Thursday, June 4, 2020 at 6:38:23 PM UTC-4, Kenz Dale wrote:

3) No chance of ripping the wings off the plane due to an
over-exuberant winch operation

That possibility is reliably eliminated by a calibrated weak link in the
winch launch rope.

Good modern winches monitor and adjust cable tension rather than blindly
using throttle position. Skylaunch units have a basic (analog?) computer
which accepts the glider type and surface wind speed before each launch.
I've yet to have a bad launch off one.


--
Martin | martin at
Gregorie | gregorie dot org

On Thursday, June 4, 2020 at 5:38:23 PM UTC-5, Kenz Dale wrote:
On Thursday, March 5, 2020 at 1:22:48 AM UTC-5, son_of_flubber wrote:
I'd rather take my chances on something that would accelerate the glider 0-50 knots in 50 meters with the FES running from the very start of the roll. This would increase available runway ahead for launch failure and conserve a bit of battery power. Fully automated with pilot pushing the go button.


This is really the idea right here. As we increasingly embrace self-launch eGliders, I think we'll see more and more gliders operating out of small airports without the benefit of a club. Thus, what's missing in the conversation is a consideration of the CONOPS (CONcept of OPerationS) for single-person launching.

Cool idea, however, it has sort of been tried before. One of our club members posted this link to a film documenting initial tests with a semi-autonomous auto-launch system. Seemed to work, but with significant wear on the launch vehicle.

https://youtu.be/wwsa4PVYMJY

https://youtu.be/wwsa4PVYMJY

Excellent.

For an FES ground assist, you need enough energy for a rope break like return to the field when the FES does not work.

I there a safe and economical way to make a winch that can just get you to 300 feet?

Might be some minor issues with the design example in the video.

On Friday, June 5, 2020 at 8:59:21 AM UTC-6, wrote:

https://youtu.be/wwsa4PVYMJY

Excellent.

For an FES ground assist, you need enough energy for a rope break like return to the field when the FES does not work.

I there a safe and economical way to make a winch that can just get you to 300 feet?

Might be some minor issues with the design example in the video.

Good and cheap are mutually exclusive. A good, safe machine won't be cheap.